Presently, as shown in FIG. 1, households may contain many different electrical appliances including, but not limited to, televisions, fire alarms, computers, telephones, microwaves, washing machines and dryers. Commonly, these appliances are distinct entities that operate without any communication with each other.
Companies are currently developing home local area networks ("home LANs") which are designed to allow control of electrical devices connected to the network through a personal computer or some other type of micro-controller with an input device for interfacing with the network, such as a touch-pad. An example of current home LAN technology is IBM's Home Director System. These systems are directed at controlling and monitoring appliances from central locations, and are limited to visual feedback through a computer monitor or LCD display.
Other companies are working on developing earcons. Earcons are icons for the ear. An earcon is a distinct audio signal which corresponds to the occurrence of a specific event. For example, after finishing a wash cycle, a washing machine emits a distinctive sound that would conjure up the image of a washing machine in the mind of a user and a microwave would emit a similarly distinct sound after finishing a cooking cycle. Audio signals have the advantage of being emitted and perceived from any direction, allowing an operator to focus on other tasks and only shift attention when the appropriate signal is perceived. The same benefit cannot be obtained in a visual indicator environment because an operator has to repeatedly focus attention on a device to look for an indication of a completed task. Also, visual indicators are rendered useless once the operator leaves the room containing the indicator.
Another benefit of assigning distinct audio signals to different devices is that it eliminates confusion when the operator of the device has multiple devices running at the same time or is in a different room than the device that is signaling. However, in order for the devices to be heard in different rooms or even on different floors of a home, it is necessary for an audio signal emitted from a device to be sufficiently loud so that it may be perceived when an individual is remote to the device, or there is a competing level of noise in the environment such as a vacuum cleaner. The required decibel level for an audio indicator to be heard throughout a wide area could be impractical or even dangerous.